Description

ecb_crypt() and cbc_crypt() implement the NBS DES (Data Encryption Standard). These routines
are faster and more general purpose than crypt(3C). They also are able
to utilize DES hardware if it is available. ecb_crypt() encrypts in ECB
(Electronic Code Book) mode, which encrypts blocks of data independently. cbc_crypt() encrypts in
CBC (Cipher Block Chaining) mode, which chains together successive blocks. CBC mode
protects against insertions, deletions, and substitutions of blocks. Also, regularities in the
clear text will not appear in the cipher text.

The first parameter, key, is the 8-byte encryption key with parity. To
set the key's parity, which for DES is in the low bit
of each byte, use des_setparity(). The second parameter, data, contains the data to
be encrypted or decrypted. The third parameter, datalen, is the length in
bytes of data, which must be a multiple of 8. The fourth
parameter, mode, is formed by OR'ing together the DES_ENCRYPT or DES_DECRYPT
to specify the encryption direction and DES_HW or DES_SW to specify software
or hardware encryption. If DES_HW is specified, and there is no hardware,
then the encryption is performed in software and the routine returns DESERR_NOHWDEVICE.

For cbc_crypt(), the parameter ivec is the 8-byte initialization vector for the
chaining. It is updated to the next initialization vector upon successful
return.

Return Values

Given a result status stat, the macro DES_FAILED is false only for
the first two statuses.

DESERR_NONE

No error.

DESERR_NOHWDEVICE

Encryption succeeded, but done in software instead of the requested hardware.